This object preferably is achieved by the characterizing features of the present invention.
Computer tomography is widespread in medical diagnostics and in material sciences. With this and with the methods known until now, computer tomopraphs are imaged from recordings of through-transmission of radiation with X-rays.
However, within the context of the present patent application, the term of a computer-tomographic measurement here includes any interaction of a measured object with an electromagnetic or corpuscular irradiation or with an acoustic wave field.
The projection data resulting from the computer-tomographic measurement is acquired with the measurement from numerous directions, and is processed with the help of a computer-assisted evaluation for imaging structural details.
According to the state of the art at present, an imaging method of “filtered back-projection” is applied for this computer-assisted evaluation. This method based on a Fourier transformation or its computer-optimized implementation demands the preparation of projection data over the full angular range of 180°0 with parallel irradiation and 360° with fan irradiation. For this reason, a complete rotation of the object amid a suitable irradiation and measurement of the interactions over the mentioned angular range is required.
In order to ensure an acceptable picture quality with an adequate local resolution, with low noise and whilst avoiding the formation of artefacts, it is further necessary with the computer-tomographic measurement to apply a high angular resolution over the complete angular range, i.e. to keep the angular distance between adjacent “individual measurements” during a computer-tomographic measurement procedure as low as possible. At the same time these methods process the signal noise basically at the expense of the local resolution.
A grave disadvantage which stems from this last mentioned high sensitivity of the method to noise, as well as from required high angular resolution on measurement, and from the wide angular range which must be acquired, is a high irradiation dose which has a negative effect on the costs of a measurement and in particular also on the health of the patient with medical applications.